Portable unit for thin-layer chromatographic analysis



Oct. 20, 1970 A. D. BAITSHOLTS 3,535,036

PORTABLE UNIT FOR THIN-LAYER CHROMATOGRAPHIC ANALYSIS Filed Oct. 31,1967 INVENTOR ALBERT D. BAITSHOLTS FIG. 3

ATTORNEYS Patented Oct. 20, 1970 3,535,086 PORTABLE UNIT FOR THIN-LAYERCHROMATOGRAPHIC ANALYSIS Albert E). Baitsholts, Rochester, N.Y.,assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of NewJersey Filed Oct. 31, 1967, Ser. No. 679,323 Int. Cl. B01d /08 U.S. Cl.23-253 16 Claims ABSTRACT OF THE DISCLOSURE Apparatus for use inthin-layer chromatography comprising a substantially enclosed chamberformed by two sheets, a chromatographic sheet and a cover sheet,attached one to each side of a continuous, for example, a rectangular,frame. The apparatus may be made as a self-contained unit by mountingcapsules in the chamber containing migrating solvent or other necessarychemicals and including devices for opening the capsules at will fromoutside the chamber.

BACKGROUNDFIELD OF THE INVENTION This invention relates tochromatography. In particular it relates to an improved simplifieddevice for use in thin-layer chromatography, which device may beconstructed as a self-contained unit for field use or the like.

BACKGROUNDDESCRIPTION OF THE PRIOR ART A modern form of chromatographyis the so-called thin-layer chromatography. The name is based on the useof a sorption agent, usually an adsorption agent, in the form of a thinlayer or an inert support. This arrangement possesses a number of knownadvantages as compared to other chromatography techniques such as paperchromatography, adsorption columns, etc.

One type of apparatus designed especially for use with thin-layerchromatography is that shown in US. Pat. No. 3,189,541 to Brenner et al.issued June 15, 1965. In the apparatus of Brenner et al. the thin-layerchromatographic adsorbent is coated on the surface of a plate of glassafter which a thin gasket is placed along three edges of the plate and asecond glass plate is placed over the adsorbent layer forming a thinlayer or air gap between the two plates. The sandwich is held togetherby clamps placed about the sealed sides. This thin chamber equilibratesquickly with solvent vapor when the chromatogram is developed by placingthe open end of the sandwich in a trough containing the migratingsolvent. The quick and near complete saturation provided by this thinsandwich chamber is important in achieving optimum results fromchromatographic analysis.

However, this previously known sandwich-type chromatographic chamber hasat least one serious disadvantage in that it is quite inconvenient tooperate. Operation of the apparatus requires many manipulative steps,that is, coating the first plate, arranging the gaskets and the secondplate over the first plate, clamping the plates together, setting up thetrough with the solvents, and linking the solvent with the adsorbentlayer. Consequently, this apparatus would not lend itself to use outsideof the laboratory.

SUMMARY OF THE INVENTION It is a purpose of the present invention toprovide a sandwich-type chamber for use in thin-layer chromatographicanalysis which is far more simple to use than apparatus knownheretofore. It is a further purpose of the present invention to providea sandwich-type, thinlayer chromatographic chamber which may beconstructed as a self-contained unit containing not only thechromatographic sheet, but also the migrating solvent and all otherelements required to carry out the chromatographic analysis, so that theunit may be conveniently used away from the laboratory for on-the-spottesting.

According to the present invention there is provided a chromatographicdevice comprising a frame member surrounding a chamber area and havingtwo generally open parallel sides. While it is contemplated that theframe will be generally rectangular, the invention is not necessarilylimited to a rectangular frame. Within this frame member the chamberproper is formed by attaching two sheets to the generally parallel sidesof the frame. First, a chromatographic sheet comprising a smooth flatsupport sheet with a sorbent layer adhered to and covering one surfacethereof is attached to one side of the frame with the sorbent layerfacing the interior of the chamber. Next, a cover sheet is placed overthe other side of the frame. The particular characteristics of the coversheet are not critical. However, it would almost always be desirable toform the same from a substantially transparent material so that theprogress of the chromatographic analysis could be visually observed. Thechamber formed between the two sheets should be as thin as is practicalso that the volume of the chamber will be small, whereby rapidequilibration will be achieved when the migrating solvent is released inthe chamber to develop the chromatogram.

To render the device self-sufiicient for use in the field away from thelaboratory, the migrating solvent is mounted in a capsule right in thechamber itself. Among suitable solvents from which to select forspecific analyses are benzene, chloroform, alcohols, butanol-aceticacidwater, and propanol-ammonia. The capsule is provided with a weakenedportion, tit, or plug which is connected to a wire or thread extendingoutside of the chamber so that by merely pulling the wire or thread thesolvent can be released from the capsule and allowed to come intocontact with the chromatogram sheet. For example, in one embodiment ofthe invention the capsule is mounted on a column attached to the framewith the weakened portion located at the bottom so that when the wire orthread is pulled solvent will fall to the bottom of the chamber.Preferably an absorbent pad is provided at the bottom of the chamber toprevent splashing of the solvent and to permit a more uniform movementof the solvent onto the sorbent layer of the chromatogram sheet.

Additionally, if desired, further provision may be made within thechamber to render the same completely selfsufiicient for fieldapplication. For example, a visualization reagent which reacts withcolorless compounds after the chromatographic separation to render themvisible may be included in the chamber. The visualization reagent may beincorporated in the same capsule as the migrating solvent, e.g.butanol-acetic acid-water containing 0.2% ninhydrin. Alternatively, thevisualization reagent may be added in a second capsule or incorporatedin the sorbent layer. Furthermore, means may be provided, if desired,for indicating or reducing the moisture level within the chamber.

To operate the apparatus of this invention, the sample to be tested isadded to the sorbent layer by passing a hypodermic needle or syringethrough a small hole in either the cover sheet (unless, of course, it isa hard material such as glass) or through from the back of the supportsheet. Solvent is then introduced, and, after development, thechromatogram is peeled off and removed by suitable means such as bypulling a tab provided on the periphery of the support sheet extendingoutwardly away from the frame.

Thus, it is an object of this invention to provide an improved devicefor thin-layer chromatography which overcomes disadvantages ofconventional apparatus known heretofore.

It is another object of this invention to provide a simplified apparatusfor carrying out chromatographic separations in the field, away fromlaboratory facilities, special apparatus, or the like.

It is still another object of this invention to provide a completelyself-contained unit for thin-layer chromatographic analysis in thefield. It is still another object of this invention to provide asimplified and compact thin-layer chromatography apparatus which is sosimple in design and low in cost that a single use followed bydiscarding of the apparatus would be practical.

It is still another object of this invention to provide an improvedsandwich-type thin-layer chromatographic apparatus comprising a chamberformed between two sheets, a chromatogram sheet and a cover sheet, thesheets being separated by a spacing frame which frame together with thesheets forms a substantially enclosed chamber.

Other objects and the attendant advantages of the present invention willbecome apparent from the detailed description to follow together withthe accompanying drawings which describe and illustrate a preferredembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view illustrating a chromatographic device inaccordance with this invention.

FIG. 2 is a vertical sectional view taken along line 2-2 of FIG. 1.

FIG. 3 is a fragmentary vertical sectional view similar to FIG. 2showing a modified arrangement for mounting the solvent capsule.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingsthere is shown in FIGS. 1 and 2 a chromatography apparatus including aframe 11. Although the frame may be of any convenient shape, in thepreferred embodiment of the invention it is rectangular and includes apair of side edges 12, a top 13 and a bottom 14. The frame may be formedof any suit able material which is inert with respect to the particularmigrating solvent or to other chemicals to be used during thechromatographic analysis. Suitable materials for construction of theframe include solvent resistant plastics such as polyethylene,polypropylene, polyethylene terephthalate, Teflon, nylon, polycarbonate,polystyrene, and Lucite. The frame is preferably made of a thermoplasticmaterial so that it can be heat-sealed or solvent-sealed together, andsimilarly sealed to the remainder of the apparatus to be describedbelow.

A thin-layer chromatogram sheet 15 comprising a smooth fiat supportsheet or backing 16 and a sorbent layer 17 is attached to the back edgeof frame 11 to close off that side. If the backing 16 is of athermoplastic material then the sheet 15 can be heat-sealed to the frame11. Alternatively, a suitable bonding cement or glue 18 may be employedat the lines of contact between the sheet 15 and the frame 11. The sheet15 may be marked at points 17a to indicate the spots where the samplematerial is to be placed. The sheet 15 also includes a tab 19 extendingoutwardly from the frame for peeling off and removing the chromatogramfrom the frame after development, for purposes of measurement,visualization, storage, etc. Of course, if desired, and if operatingconditions permit, the backing 16 could also be a hard non-thermoplasticmaterial such as glass.

A cover sheet 21, of corresponding geometric configuration to sheet 15,is attached to the front edge of frame 11 to act together with frame 11and sheet 15 to form a substantially enclosed chamber. The cover sheet21 should have certain characteristics in common with the frame, namely,resistance to the migrating solvent and to other chemicals used duringthe chromatographic analysis, and heat or solvent scalability forfacilitating its connection to frame 11. Moreover, cover sheet 21 shouldbe substantially transparent so that the chromatogram may be observedvisually. Of course, if desired, the cover sheet could also be formed ofa hard non-thermoplastic material such as glass. In this case coversheet 21 would be attached to frame 11 by suitable bonding material 20.

There has been described above an arrangement which provides asubstantially improved chamber for carrying out a chromatographicanalysis. It is compact and far more convenient to use than chambersknown heretofore.

A further important feature of the present invention is that the devicemay be constructed so as to include the migrating solvent, or othernecessary chemical reagents, within the chamber, thereby rendering itcompletely self-sufficient and suitable for use in the field, such as ina doctors ofiice, crime laboratory, production areas, or other remotelocations lacking extensive facilities.

A preferred arrangement for mounting the solvent within the chamber isshown in the drawings. A capsule 25 of thin glass or plastic havingmigrating solvent 26 contained therein is attached to a column 27extending from the top 13 to the bottom 14 of frame 11. The capsule 25includes a weakened portion, a tit, or a plug 28 connected by a threador wire 29 through an aperture 30 in frame 11 to a tab 31. By simplypulling tab 31 and breaking the weakened portion or tit, or pulling outthe plug, the capsule 25 can be opened to release the migrating solvent26 onto the bottom 14 of the chamber. Alternatively, the solvent capsu ecan be opened by squeezing through the sides of the chamber, orpenetrating it with a needle from outside. An absorbent pad 35 can beprovided on the bottom 14 of the chamber for receiving the solvent 26 insuch a manner as to prevent splashing, and also to permit a more uniformmigration of the solvent onto sorbent layer 17.

Within the spirit and scope of the invention numerous variations andmodifications are possible. Some of these are shown in phantom lines inthe drawings. For example, the chamber may also include means formounting therein suitable visualization reagents (these may be liquidssuch as ninhydrin or gases such as ammonia or iodine vapor). Thevisualization reagent may be incorporated in the same capsule as themigrating solvent, or in a coated layer on the sorbent layer 17, or in aseparate capsule such as capsule 40 shown in the drawings. Capsule 40may be an aerosol spray bottle having a valve, or it may include aweakened portion, tit, or plug. A thread or wire 41 extending from thevalve or other means through the frame 11 to a tab 42 is operated in asimilar manner to thread or wire 29.

For controlling moisture content within the chamber, an indicator meanssuch as commercially available indicating silica gel containing cobaltcompounds of changeable color, shown in phantom lines as 45, can beincluded within the chamber. Also, desiccant material stronger than theadsorbent can be used to maintain dry conditions in the chamber.

Since the sorbent layer is within an enclosed chamber in the apparatusof this invention, it is possible to maintain the sorbent layer in anactive condition for prolonged periods, thereby eliminating the usualprocedure of activating or otherwise pretreating the sorbent layerimmediately prior to use. Another advantage of the sealed chamber isthat it acts as a protective enclosure for the sorbent which is highlyactive and would tend to pick up impurities if exposed to the air or tosome packaging materials. A still further advantage stemming from thefact that the sorbent layer is within an enclosed chamber is that astandard or reference compound, prespotted on the sorbent layer, can beused for comparison with the samples.

In an alternate embodiment of the invention, as shown in FIG. 3, asolvent capsule 25 is attached to the frame 11 by bands of adhesive tape51, 52, or the like, which are secured between one of the side sheets 21and the adjacent edges of the frame at top and bottom (or oppositesides). The bottom of the bottle 25' has a weakened portion, tit or plug28' which can be broken or removed by pulling a wire or thread 29extending through an opening in frame 11' to a tab.

The preferred embodiment of the invention described herein is operatedas follows. The apparatus is first sealed together, with migratingsolvent encapsulated therein, thereby forming a self-sustainedsandwich-type chromatographic developing chamber. The sample mixture tobe separated is then spotted on the marks 17a provided on the sorbentlayer 17 by passing either a syringe or a hypodermic needle throughsheet 15 or sheet 21. Alternatively, small holes can be formed in onesheet and then covered with adhesive tape which can later be pushed backto permit a syringe or needle to pass therethrough. After the sampleshave been placed on the spots 17a, and with the chamber in an uprightposition, the tab 31 is pulled to release the solvent 26 to fill thelower part of the chamber, splashing being prevented by absorbent pad 35on the bottom 14 of the chamber. The solvent fills the lower part of thechamber and immediately begins to rise through the sorbent layer 17 bycapillary action, carrying with it the components of the mixture to beseparated. After separation has been completed, tab 19 is pulled toremove the chromatogram from the frame 11 for measurement,visualization, etc.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

I claim:

1. A device for conducting thin-layer chromatographic separation,comprising:

a smooth flat support sheet,

a thin chromatographically-active sorbent layer adhered to and coveringone surface of said support sheet,

a cover sheet of corresponding geometrical configuration to said supportsheet disposed with one surface thereof opposite said sorbent layer andin proximity thereto,

frame means secured to and spacing said support sheet and said coversheet to form therewith a substantially enclosed chamber,

a capsule of migrating solvent mounted in said chamber, and

means operable from outside said chamber extending therein for openingsaid capsule and releasing said solvent, whereby said solvent is broughtinto contact with said sorbent layer to effect chromatographicseparation.

2. A device as described in claim 1 wherein each of said support sheet,cover sheet and frame means is rectangular in shape.

3. A device as described in claim 1 wherein said support sheet includesa tab portion extending beyond said frame means for removing thechromatogram after development.

4. A device as described in claim 1 wherein said cover sheet issubstantially transparent.

5. A device as described in claim 1 including a column within saidchamber connected to said frame means, said capsule being mounted onsaid column.

6. A device as described in claim 1 including a strap for supportingsaid capsule passing over said capsule and extending in oppositedirections therefrom, with the ends thereof being held between one ofsaid sheets and said frame means.

7. A device as described in claim 1 including the absorbent pad on thebottom of said chamber for receiving said solvent after release fromsaid capsule.

8. A device as described in claim 1 including means within said chamberfor regulating the moisture content thereof.

9. A device as described in claim 8 wherein said means for regulatingthe moisture content within said chamber is a dessicant.

10. A device as described in claim 1 wherein said means for opening saidcapsule is a wire having one end thereof connected to said capsule andthe other end thereof extending outside said chamber.

11. A device as described in claim 10, wherein said capsule includes aplug closing an opening therein, said plug being connected to said wire.

12. A device as described in claim 10 wherein said capsule includes aweakened portion to which said wire is connected.

13. A device as described in claim 1 including a visualization reagentwithin said chamber for effecting reaction with colorless compoundsundergoing chromatographic separation to render them visible.

14. A device as described in claim 13 wherein said visualization reagentis incorporated within said capsule of migrating solvent.

15. A device as described in clai m13 wherein said visualization reagentis contained within a capsule which is separate to said capsule ofmigrating solvent and mounted within said chamber.

16. A device as described in claim 13 wherein said visualization reagentis incorporated within said sorbent layer.

References Cited UNITED STATES PATENTS 3,189,541 6/1965 Brenner.

3,449,083 6/ 1969 Pelick 232S3 FOREIGN PATENTS 1,370,780 7/1964 France.

JOSEPH SCOVRONEK, Primary Examiner S. MARANTZ, Assistant Examiner US.Cl. X.R. 73-611; 2l0198

